1. Field of the Invention
The present invention relates to weld repair, and, more particularly, the present invention relates to weld repair of irradiated materials susceptible of primary water stress corrosion cracking
2. Description of the Related Art
Over the past approximately 15 years, the commercial nuclear power industry has been required to perform examinations of Inconel® 600 nozzles and Inconel® 82/182 welds due to the emergence of primary water stress corrosion cracking (PWSCC), as these materials are known to be susceptible to PWSCC in the environment in which these materials are commonly exposed to within a nuclear pressurized water reactor (PWR), In many cases, repairs of these nozzles and welds have been required as the examinations have revealed minor indications/discontinuities or, in a small number of cases, minor leakage of the reactor coolant. Numerous repair methods have been utilized in the industry in order to repair the Inconel® 600 nozzles and associated attachment welds, and many of the welds which have been repaired within the industry are of a partial penetration J-groove type geometry. The full penetration welded nozzles, as shown in FIG. 1, present a unique set of challenges when evaluating the application of a known repair method in the industry.
One possible known repair method which could be applied to the full penetration welded nozzle is to apply a structural weld overlay o the outside of the piping or vessel with the overlay covering the full extents of the susceptible nozzle and weld material with substantial overlap onto the piping or vessel. For this application, the existing nozzle would be removed approximately flush with the outer surface of the piping or vessel. The overlay would then be applied to cover the full extents of the remaining nozzle and existing susceptible weld material with overlap onto the piping or vessel. A bore is then machined into the new weld overlay to accept a replacement nozzle fabricated from PWSCC-resistant materials, The thickness and size of the overlay, based upon ASME Boiler & Pressure Vessel Code Section rules, would ultimately result in a significant volume of weld material being applied to the location. This inherently results in long schedule duration for welding, potential for high personnel radiation exposure, and high risks of potential welding issues as a result of depositing such a large PWSCC-resistant nickel alloy weld overlay.